Studies on Hepatic Transport and Metabolism of Bilirubin, Bile Acids, and Other Organic Substances.

为了阐明肝细胞运输和有机离子代谢及其与临床医学的相关性，我们进行了以下研究。(1)研究了正常和先天性黄疸卫材高胆红素尿大鼠肝细胞小管膜泡（CMV）对胆汁中有机阴离子普伐他汀（pravastatin）的摄取。普伐他汀的摄取在ATP和跨膜向上pH梯度的共同存在下被刺激。EHBR中不存在这种转运。这些结果表明，该转运系统可能通过管膜进行有机阴离子的生理转运。(2)结扎胆管（BDL），观察放射性标记牛磺胆酸盐和普伐他汀的摄取情况。BDL后2天，两种转运均明显下降。这将为临床医学中梗阻性黄疸释放后胆流量减少提供病理生理学依据。(3) Gilbert综合征和II型Crigler-Najjar综合征的特点是肝微粒体胆红素udp -葡萄糖醛酸糖基转移酶（BUGT; ugt1 ^<** bbb1）活性分别下降到正常水平的30%和10%。对BUGT基因的分析主要集中在Gilbert综合征，在编码区发现杂合错义突变或在启动子区发现纯合TATA box突变（存在额外的TA）。这些结果表明，吉尔伯特综合征是作为显性和隐性性状遗传的。(4)在转子综合征患者的肝脏中，我们未发现谷胱甘肽s -转移酶（GST）的免疫组化染色，表明肝细胞中缺乏全GST同工酶。(5)参考有关胆红素等有机阴离子代谢转运的文献，对上述结果进行了讨论。

To elucidate hepatocyte transport and metabolism of organic ions and its relevance to clinical medicine, the following studies were perfomed. (1) Uptake of pravastatin, an organic anion excreted into bile, by hepatocyte canalicular membrane vesicles (CMV) from normal and congenitally jaundiced Eisai hyperbilirubinuria rats (EHBR) was studied. Pravastatin uptake was stimulated in the co-presence of ATP and transmembrane upward pH gradient. This transport was absent in EHBR.These results indicate that this transport system may physiologically transport organic anions through canalicular membrane.(2) Bile canalicles were ligated (BDL) and uptakes of radiolabeled taurocholate and pravastatin were observed. Both of the transports decreased markedly 2 days after BDL.This will give pathophysiological basis for reduced bile flow after release of obstrucrive jaundice in clinical medicine. (3) Gilbert's and Type II Crigler-Najjar syndromes are characterized by the decrease in te hepatic microsomal bilirubin UDP-glucuronosyltransferase (BUGT ; UGT 1^<**>1) to 30 and 10 % of the normal activity, respectively. The genes for BUGT was analyzed mainly in Gilbert's syndrome, and heterozygous mis-sense mutations were found in the coding region or homozygous TATA box mutation (presence of additional TA) was found in the promoter region in the most of the cases. These results indicate that Gilbert's syndrome is inherited both as a dominant and a recessive trait.(4) In the liver of patients with Rotor's syndrome, we found no immunohistochemical staining of glutathione S-transferase (GST), indicating the absence of whole GST isozymes in the hepatocytes. (5) The above results were discussed refering to the litratures on the metabolism and transport of bilirubin and other organic anions.